Fighting ignorance since 1973.(It's taking longer than we thought.)

Is fluoride in water a good thing or a danger?

February 2, 2007

Dear Cecil:

In 2002 you said, "Long a target of fringe groups, fluoridation is widely considered one of the great public-health achievements of the last century." My wife has shown me a lot of Internet back-and-forth suggesting a host of problems that can be blamed on fluoridation. Some say fluoride is industrial waste and that the mining industry duped us into thinking it's healthy so we'd want it in our water. So is fluoride deadly or healthy, or do we just not know?

James B., Columbia, Maryland

Illustration by Slug Signorino

Cecil replies:

Oh, we’ve got a pretty fair idea. Fact is, like a lot of things (Tylenol and water come to mind), fluoride can be either good or bad for you depending on how much you get. In small amounts the stuff is definitely salubrious. Though a few holdouts still argue, most research I’ve seen credits fluoridation with the sharp drop in tooth decay seen throughout the developed world over the past 40 years. In the U.S., 67 percent of those drinking public water get fluoride in it and tooth decay has fallen 68 percent since the late 60s, leading the Centers for Disease Control to call water fluoridation one of the top ten public-health achievements of the 20th century. Too much of a good thing, on the other hand – and we’re talking milligrams per kilo of body weight, not gallons – and you’ve got problems, ranging from stained teeth and upset stomach to death.

Although fluoride’s contribution to healthy teeth had been suspected earlier, the guy chiefly responsible for getting people to focus on the usefulness of having it in drinking water is Dr. Frederick McKay, who in 1909 began investigating a tooth discoloration so common among residents of Colorado Springs that it was known as “Colorado brown stain.” After peering into the mouths of nearly 3,000 kids in the area and finding that 87 percent had stained teeth, McKay and colleagues went on to establish that (a) such teeth were unusually resistant to serious cavities and (b) the cause of both phenomena was the naturally high fluoride level in the local water supply. After further research showed that one part per million of fluoride in drinking water reduced tooth decay with minimal risk of stained teeth, Grand Rapids, Michigan, became the first city to artificially fluoridate its water in 1945. Thousands of other municipalities have done so since.

For years antifluoridationists were mainly paranoids who thought it was all a Bolshevik plot. Today they’re still paranoid, but they’ve polished up their arguments. A sample:

1. Fluoride is industrial/mining waste. Fluorosilicic acid, a common fluoridating agent, is a by-product of phosphate fertilizer production, and phosphates are mined, so technically I guess you could say fluoride is mining waste. Big deal. Lots of useful commodities are made as a by-product of other processes, such as gypsum from burning coal and molasses from sugar refining. The suggestion that fertilizer tycoons have suckered the country into fluoridating drinking water to simplify disposal of their toxic waste is, to be gentle, a reach.

2. Fluoride can be poisonous. Yup. In 1993 dozens of Mississippi residents were sickened by tap water with fluoride levels as much as 200 times the recommended amount; the year before, an accident at an Alaskan water treatment plant resulted in one death due to fluoride poisoning. A toddler who scarfs a tube of fluoridated toothpaste risks acute fluoride toxicity, symptoms of which include the aforementioned stomach upset or worse. True, these are overdoses and thus preventable with reasonable care, but you’ll also find claims that long-term exposure to lesser amounts of fluoride can lead to skeletal and kidney damage, learning disabilities and brain disorders, thyroid problems, allergies, and birth defects including Down syndrome. Notwithstanding the occasional disturbing finding, support for these contentions is weak, although the CDC did issue a statement that one study showed a potential increase in osteosarcoma, a rare bone cancer, in young males who drink fluoridated water.

3. Fluoridation has been (literally) shoved down the throat of the American public. This one’s the toughest to refute. The dirty little secret among water fluoridation advocates is that while tooth decay has declined dramatically in places that fluoridate their water, it’s dropped equally fast in places that don’t. There’s some debate about why, but surely in large part it’s because people who don’t get fluoride out of the tap are getting it from other sources, including not just fluoridated toothpaste but, in countries such as Germany and France, fluoridated table salt. If Sylvie or Fritz worries that fluoride will make their hair fall out, they can buy nonfluoridated products. Americans drinking fluoridated water don’t have that option. Water fluoridation advocates say never mind the philosophy, we’ve got a system that works, don’t fix it if it ain’t broke, etc. Fine, but it’s odd to have Europeans advocating choice while here in the land of liberty we know what’s good for you, so shut up and drink.